Sealing member for prosthetic heart valve

ABSTRACT

A prosthetic heart valve includes an annular frame that has an inflow end and an outflow end and is radially compressible and expandable between a radially compressed configuration and a radially expanded configuration. The prosthetic heart valve further includes a leaflet structure positioned within the frame and secured thereto, and an outer sealing member mounted outside of the frame and adapted to seal against surrounding tissue when the prosthetic heart valve is implanted within a native heart valve annulus of a patient. The sealing member can include a mesh layer and pile layer comprising a plurality of pile yarns extending outwardly from the mesh layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 15/991,325 filed on May 29, 2018, which claims the benefit ofU.S. Patent Application No. 62/513,348, filed on May 31, 2017. Theentire contents of the foregoing applications are incorporated herein byreference.

FIELD

The present disclosure relates to implantable, expandable prostheticdevices and to methods and apparatuses for such prosthetic devices.

BACKGROUND

The human heart can suffer from various valvular diseases. Thesevalvular diseases can result in significant malfunctioning of the heartand ultimately require replacement of the native valve with anartificial valve. There are a number of known artificial valves and anumber of known methods of implanting these artificial valves in humans.Because of the drawbacks associated with conventional open-heartsurgery, percutaneous and minimally-invasive surgical approaches aregarnering intense attention. In one technique, a prosthetic valve isconfigured to be implanted in a much less invasive procedure by way ofcatheterization. For example, collapsible transcatheter prosthetic heartvalves can be crimped to a compressed state and percutaneouslyintroduced in the compressed state on a catheter and expanded to afunctional size at the desired position by balloon inflation or byutilization of a self-expanding frame or stent.

A prosthetic valve for use in such a procedure can include a radiallycollapsible and expandable frame to which leaflets of the prostheticvalve can be coupled. For example, U.S. Pat. Nos. 6,730,118, 7,393,360,7,510,575, and 7,993,394, which are incorporated herein by reference,describe exemplary collapsible transcatheter heart valves (THVs).

A challenge in catheter-implanted prosthetic valves is the process ofcrimping such a prosthetic valve to a profile suitable for percutaneousdelivery to a subject. Another challenge is the control of paravalvularleakage around the valve, which can occur for a period of time followinginitial implantation.

Paravalvular leakage has been a known problem since the firstreplacement valves were introduced. The earliest prosthetic heartvalves, those that were implanted surgically, included a circumferentialsewing ring that was adapted to extend into spaces in the tissuesurrounding the implanted prosthesis to prevent paravalvular leaking.For example, U.S. Pat. No. 3,365,728 describes a prosthetic heart valvefor surgical implantation that includes a rubber “cushion ring” thatconforms to irregularities of the tissue to form an effective sealbetween the valve and the surrounding tissue. From there, vascularstents or stent grafts were developed that could be implanted bynon-surgical catheterization techniques. These stents included a fabriccovering that allowed the stent to be used to isolate and reinforce thewall of a blood vessel from the lumen of the vessel. These fabriccoverings served essentially the same purpose on stents as did thesealing rings on surgical heart valves—they reduced the risk of bloodleaking between the prosthesis and the surrounding tissue. Multiplegraft designs were developed that further enhanced the external seal toprevent blood from flowing between the graft and surroundingcardiovascular tissue. For example, U.S. Pat. No. 6,015,431 to Thorntondiscloses a seal secured to the outer surface of a stent that is adaptedto occlude leakage flow externally around the stent wall between theouter surface and the endolumenal wall when the stent is deployed, byconforming to the irregular surface of the surrounding tissue. U.S.Patent Publication 2003/0236567 to Elliot similarly discloses a tubularprosthesis having a stent and one or more fabric “skirts” to sealagainst endoleaks. U.S. Patent Publication 2004/0082989 to Cook et al.also recognized the potential for endoleaks, and describes a stent grafthaving a cuff portion that has an external sealing zone that extendsaround the body of the stent to prevent leakage. The cuff portion couldbe folded over to create a pocket that collects any blood passing aroundthe leading edge of the graft to prevent an endoleak.

Building on this technology, in the late 1980's, the first permanentbioprosthetic heart valve was implanted using transcatheter techniques.U.S. Pat. No. 5,411,552 to Andersen describes a THV comprising a valvemounted within a collapsible and expandable stent structure. Certainembodiments have additional graft material used along the external andinternal surface of the THV. As with stent grafts, the covers proposedto be used with THVs were designed to conform to the surface of thesurrounding tissue to prevent paravalvular leaks.

Like with stents, “cuffs” or other outer seals were used on THVs. U.S.Pat. No. 5,855,601 to Bessler describes a self-expanding THV having acuff portion extending along the outside of the stent. Upon collapse ofthe stent for delivery, the outer seal collapses to form pleats, thenexpands with the stent to provide a seal between the THV and thesurrounding tissue.

Thereafter, a different THV design was described by Pavcnik in U.S.Patent Application Publication 2001/0039450. The enhanced sealingstructure of Pavcnik is in the form of corner “flaps” or “pockets”secured to the stent at the edges of each “flap” or “pocket” andpositioned at discrete locations around the prosthesis. The corner flapwas designed to catch retrograde blood flow to provide a better sealbetween the THV and the vessel wall, as well as to provide an improvedsubstrate for ingrowth of native tissue.

Thus, fabric and other materials used to cover and seal both internaland external surfaces of THVs and other endovascular prostheses such asstents and stent grafts are well known. These covers can be made withlow-porosity woven fabric materials, as described, for example, by U.S.Pat. No. 5,957,949 to Leonhardt et al., which describes a valve stenthaving an outer cover that can conform to the living tissue surroundingit upon implantation to help prevent blood leakage.

Several more recent THV designs include a THV with an outer covering.U.S. Pat. No. 7,510,575 to Spenser discloses a THV having a cuff portionwrapped around the outer surface of the support stent at the inlet. Thecuff portion is rolled up over the edge of the frame so as to provide a“sleeve-like” portion at the inlet to form a cuff over the inlet thathelps prevent blood leakage. U.S. Pat. No. 8,002,825 to Letac andCribier describes an internal cover that extends from the base of thevalve to the lower end of the stent and then up the external wall of thestent so as to form an external cover. The single-piece cover could bemade with any of the materials disclosed for making the valve structure,which include fabric (e.g., Dacron), biological material (e.g.,pericardium), or other synthetic materials (e.g., polyethylene).

While covers used on the external surface of an endovascular prosthesisto prevent paravalvular leaking are well known, there remains a need forimproved coverings that provide enhanced sealing while still providing asmall profile suitable for percutaneous delivery to a patient.

SUMMARY

Embodiments of a radially collapsible and expandable prosthetic valveare disclosed herein that include an improved outer skirt for reducingperivalvular leakage, as well as related methods and apparatusesincluding such prosthetic valves. In several embodiments, the disclosedprosthetic valves are configured as replacement heart valves forimplantation into a subject.

In one representative embodiment, a prosthetic heart valve comprises anannular frame that comprises an inflow end and an outflow end and isradially compressible and expandable between a radially compressedconfiguration and a radially expanded configuration. The prostheticheart valve further includes a leaflet structure positioned within theframe and secured thereto, and an outer sealing member mounted outsideof the frame and adapted to seal against surrounding tissue when theprosthetic heart valve is implanted within a native heart valve annulusof a patient. The sealing member can comprise a mesh layer and pilelayer comprising a plurality of pile yarns extending outwardly from themesh layer.

In some embodiments, the mesh layer comprises a knit or woven fabric.

In some embodiments, the pile yarns are arranged to form a looped pile.

In some embodiments, the pile yarns are cut to form a cut pile.

In some embodiments, the height of the pile yarns varies along a heightand/or a circumference of the outer skirt.

In some embodiments, the pile yarns comprise a first group of yarnsalong an upstream portion of the outer skirt and a second group of yarnsalong a downstream portion of the outer skirt, wherein the yarns of thefirst group have a height that is less than a height of the yarns of thesecond group.

In some embodiments, the pile yarns comprise a first group of yarnsalong an upstream portion of the outer skirt and a second group of yarnsalong a downstream portion of the outer skirt, wherein the yarns of thefirst group have a height that is greater than a height of the yarns ofthe second group.

In some embodiments, the pile yarns comprise a first group of yarnsalong an upstream portion of the outer skirt, a second group of yarnsalong a downstream portion of the outer skirt, and a third group ofyarns between the first and second group of yarns, wherein the yarns ofthe first and second groups have a height that is greater than a heightof the yarns of the third group.

In some embodiments, the prosthetic heart valve further comprises aninner skirt mounted on an inner surface of the frame, the inner skirthaving an inflow end portion that is secured to an inflow end portion ofthe outer sealing member.

In some embodiments, the inflow end portion of the inner skirt iswrapped around an inflow end of the frame and overlaps the inflow endportion of the outer sealing member on the outside of the frame.

In some embodiments, the mesh layer comprises a first mesh layer and theouter sealing member further comprises a second mesh layer disposedradially outside of the pile layer.

In some embodiments, the outer sealing member is configured to stretchaxially when the frame is radially compressed to the radially compressedstate.

In some embodiments, the mesh layer comprises warp yarns and weft yarnswoven with the warp yarns, and the pile layer comprises the warp yarnsor the weft yarns of the mesh layer that are woven or knitted to formthe pile yarns.

In some embodiments, the mesh layer comprises a woven fabric layer andthe pile layer comprises a separate pile layer that is stitched to thewoven fabric layer.

In some embodiment, the mesh layer has a first height extending axiallyalong the frame and the pile layer comprises a second height extendingaxially along the frame, wherein the first height is greater than thesecond height.

In some embodiment, the mesh layer extends closer to the outflow end ofthe frame than the pile layer.

In another representative embodiment, a prosthetic heart valve comprisesan annular frame that comprises an inflow end and an outflow end and isradially compressible and expandable between a radially compressedconfiguration and a radially expanded configuration. The prostheticheart valve further comprises a leaflet structure positioned within theframe and secured thereto, an outer sealing member mounted outside ofthe frame and adapted to seal against surrounding tissue when theprosthetic heart valve is implanted within a native heart valve annulusof a patient. The sealing member can comprise a fabric having a variablethickness.

In some embodiments, the thickness of the fabric layer varies along aheight and/or a circumference of the outer sealing member.

In some embodiments, the fabric comprises a plush fabric.

In some embodiments, the fabric comprises a plurality of pile yarns andthe height of the pile yarns varies along a height and/or acircumference of the outer skirt.

In some embodiments, the pile yarns comprise a first group of yarnsalong an upstream portion of the outer skirt and a second group of yarnsalong a downstream portion of the outer skirt, wherein the yarns of thefirst group have a height that is less than a height of the yarns of thesecond group.

In some embodiments, the pile yarns comprise a first group of yarnsalong an upstream portion of the outer skirt and a second group of yarnsalong a downstream portion of the outer skirt, wherein the yarns of thefirst group have a height that is greater than a height of the yarns ofthe second group.

In some embodiments, the pile yarns comprise a first group of yarnsalong an upstream portion of the outer skirt, a second group of yarnsalong a downstream portion of the outer skirt, and a third group ofyarns between the first and second group of yarns, wherein the yarns ofthe first and second groups have a height that is greater than a heightof the yarns of the third group.

In another representative embodiment, a prosthetic heart valve comprisesan annular frame that comprises an inflow end and an outflow end and isradially compressible and expandable between a radially compressedconfiguration and a radially expanded configuration. The prostheticheart valve further comprises a leaflet structure positioned within theframe and secured thereto, an outer sealing member mounted outside ofthe frame and adapted to seal against surrounding tissue when theprosthetic heart valve is implanted within a native heart valve annulusof a patient. The sealing member can comprise a pile fabric comprising aplurality of pile yarns, wherein the density of the pile yarns varies inan axial direction and/or a circumferential direction along the sealingmember.

In some embodiments, the pile yarns are arranged in circumferentiallyextending rows of pile yarns and the density of the pile yarns variesfrom row to row.

In some embodiments, the pile yarns are arranged in axially extendingrows pile yarns and the density of the pile yarns varies from row torow.

In some embodiments, the sealing member comprises a mesh layer and apile layer comprising the pile yarns. In some embodiments, the weavedensity of the mesh layer varies in an axial direction and/or acircumferential direction along the sealing member. In some embodiments,the mesh layer comprises one or more rows of higher-density meshportions and one or more rows of lower-density mesh portions. The one ormore rows of higher-density mesh portions and the one or more rows oflower-density mesh portions can be circumferentially extending rowsand/or axially extending rows.

In another representative embodiment, a prosthetic heart valve comprisesan annular frame that comprises an inflow end and an outflow end and isradially compressible and expandable between a radially compressedconfiguration and a radially expanded configuration. The prostheticheart valve further comprises a leaflet structure positioned within theframe and secured thereto, an outer sealing member mounted outside ofthe frame and adapted to seal against surrounding tissue when theprosthetic heart valve is implanted within a native heart valve annulusof a patient. The sealing member comprises a textile formed from aplurality fibers arranged in a plurality of axially extending rows ofhigher stitch density interspersed between a plurality of axiallyextending rows of lower stitch density. The sealing member is configuredto stretch axially between a first, substantially relaxed, axiallyforeshortened configuration when the frame is the radially expandedconfiguration and a second, axially elongated configuration when theframe is in the radially compressed configuration.

In some embodiments, each of the rows of higher stitch density canextend in an undulating pattern when the sealing member is in theaxially foreshortened configuration. When the sealing member is in theaxially elongated configuration, the rows of higher stitch density movefrom the undulating pattern toward a straightened pattern.

In another representative embodiment, a prosthetic heart valve comprisesan annular frame that comprises an inflow end and an outflow end and isradially compressible and expandable between a radially compressedconfiguration and a radially expanded configuration. The prostheticheart valve further comprises a leaflet structure positioned within theframe and secured thereto, an outer sealing member mounted outside ofthe frame and adapted to seal against surrounding tissue when theprosthetic heart valve is implanted within a native heart valve annulusof a patient. The sealing member comprises a fabric comprising aplurality of axially extending filaments and a plurality ofcircumferentially extending filaments. The sealing member is configuredto stretch axially when the frame is radially compressed from theradially expanded configuration to the radially compressedconfiguration. The axially extending filaments move from a deformed ortwisted state when the frame is in the radially expanded configurationto a less deformed or less twisted state when the frame is in theradially compressed configuration.

In some embodiments, the axially extending filaments are heat set in thedeformed or twisted state.

In some embodiments, the thickness of the sealing member decreases whenthe axially extending filaments move from the deformed or twisted stateto the less deformed or twisted state.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a prosthetic heart valve, according toone embodiment.

FIG. 2 is an enlarged, perspective view of the inflow end portion of theprosthetic heart valve of FIG. 1.

FIG. 3 is a cross-sectional view of the prosthetic heart valve of FIG.1, showing the attachment of the outer skirt to the inner skirt and theframe.

FIGS. 4-10 show an exemplary frame of the prosthetic heart valve of FIG.1.

FIGS. 11-12 show an exemplary inner skirt of the prosthetic heart valveof FIG. 1.

FIGS. 13-15 show the assembly of the inner skirt of FIG. 11 with theframe of FIG. 4.

FIGS. 16-17 show the assembly of an exemplary leaflet structure.

FIG. 18 shows the assembly of commissure portions of the leafletstructure with window frame portions of the frame.

FIGS. 19-20 show the assembly of the leaflet structure with the innerskirt along a lower edge of the leaflets.

FIGS. 21-23 are different views of an exemplary outer skirt of theprosthetic heart valve of FIG. 1.

FIG. 24-26 are cross-sectional views similar to FIG. 3 but showingdifferent embodiments of the outer skirt.

FIGS. 27-28 show an alternative way of securing an outer skirt to aninner skirt and/or the frame of a prosthetic heart valve.

FIGS. 29-32 show another way of securing an outer skirt to an innerskirt and/or the frame of a prosthetic heart valve.

FIGS. 33-35 show another embodiment of an outer sealing member for aprosthetic heart valve.

FIG. 36 shows another embodiment of an outer sealing member, shownmounted on the frame of a prosthetic heart valve.

FIG. 37 is a flattened view of a woven mesh layer of the sealing memberof FIG. 36.

FIG. 38 is a flattened view of a pile layer of the sealing member ofFIG. 36.

FIG. 39 is a flattened view of the outer surface of an outer sealingmember for a prosthetic heart valve, according to another embodiment.

FIG. 39A is a magnified view of a portion of the sealing member of FIG.39.

FIG. 40 is a flattened view of the inner surface of the sealing memberof FIG. 39.

FIG. 40A is a magnified view of a portion of the sealing member of FIG.40.

FIG. 41 is flattened view of an outer sealing member for a prostheticheart valve shown in a relaxed state when the prosthetic heart valve isradially expanded to its functional size, according to anotherembodiment.

FIG. 42 is a flattened view of the outer sealing member of FIG. 41 shownin an axially elongated, tensioned state when the prosthetic heart valveis in a radially compressed state for delivery.

FIG. 43A is a magnified view of a portion of another embodiment of anouter sealing member for a prosthetic heart valve, wherein the sealingmember is shown in a relaxed state when the prosthetic heart valve isradially expanded to its functional size.

FIG. 43B is a magnified view of the sealing member of FIG. 43A shown inan axially elongated, tensioned state when the prosthetic heart valve isin a radially compressed state for delivery.

FIG. 44A is a cross-sectional view of the fabric of the sealing memberof FIG. 43A in a relaxed state.

FIG. 44B is a cross-sectional view of the fabric of the sealing memberof FIG. 43B in a tensioned state.

DETAILED DESCRIPTION

FIG. 1 shows a prosthetic heart valve 10, according to one embodiment.The illustrated prosthetic valve is adapted to be implanted in thenative aortic annulus, although in other embodiments it can be adaptedto be implanted in the other native annuluses of the heart (e.g., thepulmonary, mitral, and tricuspid valves). The prosthetic valve can alsobe adapted to be implanted in other tubular organs or passageways in thebody. The prosthetic valve 10 can have four main components: a stent orframe 12, a valvular structure 14, an inner skirt 16, and a perivalvularouter sealing member or outer skirt 18. The prosthetic valve 10 can havean inflow end portion 15, an intermediate portion 17, and an outflow endportion 19.

The valvular structure 14 can comprise three leaflets 40 (FIG. 17),collectively forming a leaflet structure, which can be arranged tocollapse in a tricuspid arrangement. The lower edge of leaflet structure14 desirably has an undulating, curved scalloped shape (suture line 154shown in FIG. 20 tracks the scalloped shape of the leaflet structure).By forming the leaflets with this scalloped geometry, stresses on theleaflets are reduced, which in turn improves durability of theprosthetic valve. Moreover, by virtue of the scalloped shape, folds andripples at the belly of each leaflet (the central region of eachleaflet), which can cause early calcification in those areas, can beeliminated or at least minimized. The scalloped geometry also reducesthe amount of tissue material used to form leaflet structure, therebyallowing a smaller, more even crimped profile at the inflow end of theprosthetic valve. The leaflets 40 can be formed of pericardial tissue(e.g., bovine pericardial tissue), biocompatible synthetic materials, orvarious other suitable natural or synthetic materials as known in theart and described in U.S. Pat. No. 6,730,118, which is incorporated byreference herein.

The bare frame 12 is shown in FIG. 4. The frame 12 can be formed with aplurality of circumferentially spaced slots, or commissure windows, 20(three in the illustrated embodiment) that are adapted to mount thecommissures of the valvular structure 14 to the frame, as described ingreater detail below. The frame 12 can be made of any of varioussuitable plastically-expandable materials (e.g., stainless steel, etc.)or self-expanding materials (e.g., nickel titanium alloy (NiTi), such asnitinol) as known in the art. When constructed of aplastically-expandable material, the frame 12 (and thus the prostheticvalve 10) can be crimped to a radially collapsed configuration on adelivery catheter and then expanded inside a patient by an inflatableballoon or equivalent expansion mechanism. When constructed of aself-expandable material, the frame 12 (and thus the prosthetic valve10) can be crimped to a radially collapsed configuration and restrainedin the collapsed configuration by insertion into a sheath or equivalentmechanism of a delivery catheter. Once inside the body, the prostheticvalve can be advanced from the delivery sheath, which allows theprosthetic valve to expand to its functional size.

Suitable plastically-expandable materials that can be used to form theframe 12 include, without limitation, stainless steel, a biocompatible,high-strength alloys (e.g., a cobalt-chromium or anickel-cobalt-chromium alloys), polymers, or combinations thereof. Inparticular embodiments, frame 12 is made of anickel-cobalt-chromium-molybdenum alloy, such as MP35N® alloy (SPSTechnologies, Jenkintown, Pa.), which is equivalent to UNS R30035 alloy(covered by ASTM F562-02). MP35N® alloy/UNS R30035 alloy comprises 35%nickel, 35% cobalt, 20% chromium, and 10% molybdenum, by weight. It hasbeen found that the use of MP35N® alloy to form frame 12 providessuperior structural results over stainless steel. In particular, whenMP35N® alloy is used as the frame material, less material is needed toachieve the same or better performance in radial and crush forceresistance, fatigue resistances, and corrosion resistance. Moreover,since less material is required, the crimped profile of the frame can bereduced, thereby providing a lower profile prosthetic valve assembly forpercutaneous delivery to the treatment location in the body.

Referring to FIGS. 4 and 5, the frame 12 in the illustrated embodimentcomprises a first, lower row I of angled struts 22 arranged end-to-endand extending circumferentially at the inflow end of the frame; a secondrow II of circumferentially extending, angled struts 24; a third row IIIof circumferentially extending, angled struts 26; a fourth row IV ofcircumferentially extending, angled struts 28; and a fifth row V ofcircumferentially extending, angled struts 32 at the outflow end of theframe. A plurality of substantially straight axially extending struts 34can be used to interconnect the struts 22 of the first row I with thestruts 24 of the second row II. The fifth row V of angled struts 32 areconnected to the fourth row IV of angled struts 28 by a plurality ofaxially extending window frame portions 30 (which define the commissurewindows 20) and a plurality of axially extending struts 31. Each axialstrut 31 and each frame portion 30 extends from a location defined bythe convergence of the lower ends of two angled struts 32 to anotherlocation defined by the convergence of the upper ends of two angledstruts 28. FIGS. 6, 7, 8, 9, and 10 are enlarged views of the portionsof the frame 12 identified by letters A, B, C, D, and E, respectively,in FIG. 5.

Each commissure window frame portion 30 mounts a respective commissureof the leaflet structure 14. As can be seen each frame portion 30 issecured at its upper and lower ends to the adjacent rows of struts toprovide a robust configuration that enhances fatigue resistance undercyclic loading of the prosthetic valve compared to known, cantileveredstruts for supporting the commissures of the leaflet structure. Thisconfiguration enables a reduction in the frame wall thickness to achievea smaller crimped diameter of the prosthetic valve. In particularembodiments, the thickness T of the frame 12 (FIG. 4) measured betweenthe inner diameter and outer diameter is about 0.48 mm or less.

The struts and frame portions of the frame collectively define aplurality of open cells of the frame. At the inflow end of the frame 12,struts 22, struts 24, and struts 34 define a lower row of cells definingopenings 36. The second, third, and fourth rows of struts 24, 26, and 28define two intermediate rows of cells defining openings 38. The fourthand fifth rows of struts 28 and 32, along with frame portions 30 andstruts 31, define an upper row of cells defining openings 40. Theopenings 41 are relatively large and are sized to allow portions of theleaflet structure 14 to protrude, or bulge, into and/or through theopenings 40 when the frame 12 is crimped in order to minimize thecrimping profile.

As best shown in FIG. 7, the lower end of the strut 31 is connected totwo struts 28 at a node or junction 44, and the upper end of the strut31 is connected to two struts 32 at a node or junction 46. The strut 31can have a thickness S1 that is less than the thicknesses S2 of thejunctions 44, 46. The junctions 44, 46, along with junctions 64, preventfull closure of openings 40. The geometry of the struts 31, andjunctions 44, 46, and 64 assists in creating enough space in openings 41in the collapsed configuration to allow portions of the prostheticleaflets to protrude or bulge outwardly through openings. This allowsthe prosthetic valve to be crimped to a relatively smaller diameter thanif all of the leaflet material were constrained within the crimpedframe.

The frame 12 is configured to reduce, to prevent, or to minimizepossible over-expansion of the prosthetic valve at a predeterminedballoon pressure, especially at the outflow end portion of the frame,which supports the leaflet structure 14. In one aspect, the frame isconfigured to have relatively larger angles 42 a, 42 b, 42 c, 42 d, 42 ebetween struts, as shown in FIG. 5. The larger the angle, the greaterthe force required to open (expand) the frame. As such, the anglesbetween the struts of the frame can be selected to limit radialexpansion of the frame at a given opening pressure (e.g., inflationpressure of the balloon). In particular embodiments, these angles are atleast 110 degrees or greater when the frame is expanded to itsfunctional size, and even more particularly these angles are up to about120 degrees when the frame is expanded to its functional size.

In addition, the inflow and outflow ends of a frame generally tend toover-expand more so than the middle portion of the frame due to the“dog-boning” effect of the balloon used to expand the prosthetic valve.To protect against over-expansion of the leaflet structure 14, theleaflet structure desirably is secured to the frame 12 below the upperrow of struts 32, as best shown in FIG. 1. Thus, in the event that theoutflow end of the frame is over-expanded, the leaflet structure ispositioned at a level below where over-expansion is likely to occur,thereby protecting the leaflet structure from over-expansion.

In a known prosthetic valve construction, portions of the leaflets canprotrude longitudinally beyond the outflow end of the frame when theprosthetic valve is crimped if the leaflets are mounted too close to thedistal end of the frame. If the delivery catheter on which the crimpedprosthetic valve is mounted includes a pushing mechanism or stop memberthat pushes against or abuts the outflow end of the prosthetic valve(for example, to maintain the position of the crimped prosthetic valveon the delivery catheter), the pushing member or stop member can damagethe portions of the exposed leaflets that extend beyond the outflow endof the frame. Another benefit of mounting the leaflets at a locationspaced away from the outflow end of the frame is that when theprosthetic valve is crimped on a delivery catheter, the outflow end ofthe frame 12 rather than the leaflets 40 is the proximal-most componentof the prosthetic valve 10. As such, if the delivery catheter includes apushing mechanism or stop member that pushes against or abuts theoutflow end of the prosthetic valve, the pushing mechanism or stopmember contacts the outflow end of the frame, and not leaflets 40, so asto avoid damage to the leaflets.

Also, as can be seen in FIG. 5, the openings 36 of the lowermost row ofopenings in the frame are relatively larger than the openings 38 of thetwo intermediate rows of openings. This allows the frame, when crimped,to assume an overall tapered shape that tapers from a maximum diameterat the outflow end of the prosthetic valve to a minimum diameter at theinflow end of the prosthetic valve. When crimped, the frame 12 has areduced diameter region extending along a portion of the frame adjacentthe inflow end of the frame that generally corresponds to the region ofthe frame covered by the outer skirt 18. In some embodiments, thereduced diameter region is reduced compared to the diameter of the upperportion of the frame (which is not covered by the outer skirt) such thatthe outer skirt 18 does not increase the overall crimp profile of theprosthetic valve. When the prosthetic valve is deployed, the frame canexpand to the generally cylindrical shape shown in FIG. 4. In oneexample, the frame of a 26-mm prosthetic valve, when crimped, had afirst diameter of 14 French at the outflow end of the prosthetic valveand a second diameter of 12 French at the inflow end of the prostheticvalve.

The main functions of the inner skirt 16 are to assist in securing thevalvular structure 14 to the frame 12 and to assist in forming a goodseal between the prosthetic valve and the native annulus by blocking theflow of blood through the open cells of the frame 12 below the loweredge of the leaflets. The inner skirt 16 desirably comprises a tough,tear resistant material such as polyethylene terephthalate (PET),although various other synthetic materials or natural materials (e.g.,pericardial tissue) can be used. The thickness of the skirt desirably isless than about 0.15 mm (about 6 mil), and desirably less than about 0.1mm (about 4 mil), and even more desirably about 0.05 mm (about 2 mil).In particular embodiments, the skirt 16 can have a variable thickness,for example, the skirt can be thicker at at least one of its edges thanat its center. In one implementation, the skirt 16 can comprise a PETskirt having a thickness of about 0.07 mm at its edges and about 0.06 mmat its center. The thinner skirt can provide for better crimpingperformances while still providing good perivalvular sealing.

The inner skirt 16 can be secured to the inside of frame 12 via sutures70, as shown in FIG. 20. Valvular structure 14 can be attached to theskirt via one or more reinforcing strips 72 (which collectively can forma sleeve), for example thin, PET reinforcing strips, discussed below,which enables a secure suturing and protects the pericardial tissue ofthe leaflet structure from tears. Valvular structure 14 can besandwiched between skirt 16 and the thin PET strips 72 as shown in FIG.19. Sutures 154, which secure the PET strip and the leaflet structure 14to skirt 16, can be any suitable suture, such as Ethibond Excel® PETsuture (Johnson & Johnson, New Brunswick, N.J.). Sutures 154 desirablytrack the curvature of the bottom edge of leaflet structure 14, asdescribed in more detail below.

Known fabric skirts may comprise a weave of warp and weft fibers thatextend perpendicularly to each other and with one set of the fibersextending longitudinally between the upper and lower edges of the skirt.When the metal frame to which the fabric skirt is secured is radiallycompressed, the overall axial length of the frame increases.Unfortunately, a fabric skirt with limited elasticity cannot elongatealong with the frame and therefore tends to deform the struts of theframe and to prevent uniform crimping.

Referring to FIG. 12, in contrast to known fabric skirts, the skirt 16desirably is woven from a first set of fibers, or yarns or strands, 78and a second set of fibers, or yarns or strands, 80, both of which arenon-perpendicular to the upper edge 82 and the lower edge 84 of theskirt. In particular embodiments, the first set of fibers 78 and thesecond set of fibers 80 extend at angles of about 45 degrees relative tothe upper and lower edges 82, 84. Alternatively, the first set of fibers78 and the second set of fibers 80 extend at angles other than about 45degrees relative to the upper and lower edges 82, 84, e.g., at angles of15 and 75 degrees, respectively, or 30 and 60 degrees, respectively,relative to the upper and lower edges 82, 84. For example, the skirt 16can be formed by weaving the fibers at 45 degree angles relative to theupper and lower edges of the fabric. Alternatively, the skirt 16 can bediagonally cut (cut on a bias) from a vertically woven fabric (where thefibers extend perpendicularly to the edges of the material) such thatthe fibers extend at 45 degree angles relative to the cut upper andlower edges of the skirt. As further shown in FIG. 12, the opposingshort edges 86, 88 of the skirt desirably are non-perpendicular to theupper and lower edges 82, 84. For example, the short edges 86, 88desirably extend at angles of about 45 degrees relative to the upper andlower edges and therefore are aligned with the first set of fibers 78.Therefore the overall general shape of the skirt is that of a rhomboidor parallelogram.

FIGS. 13 and 14 show the inner skirt 16 after opposing short edgeportions 90, 92 have been sewn together to form the annular shape of theskirt. As shown, the edge portion 90 can be placed in an overlappingrelationship relative to the opposite edge portion 92, and the two edgeportions can be sewn together with a diagonally extending suture line 94that is parallel to short edges 86, 88. The upper edge portion of theinner skirt 16 can be formed with a plurality of projections 96 thatdefine an undulating shape that generally follows the shape or contourof the fourth row of struts 28 immediately adjacent the lower ends ofaxial struts 31. In this manner, as best shown in FIG. 15, the upperedge of the inner skirt 16 can be tightly secured to struts 28 withsutures 70. The inner skirt 16 can also be formed with slits 98 tofacilitate attachment of the skirt to the frame. Slits 98 aredimensioned so as to allow an upper edge portion of the inner skirt 16to be partially wrapped around struts 28 and to reduce stresses in theskirt during the attachment procedure. For example, in the illustratedembodiment, the inner skirt 16 is placed on the inside of frame 12 andan upper edge portion of the skirt is wrapped around the upper surfacesof struts 28 and secured in place with sutures 70. Wrapping the upperedge portion of the inner skirt 16 around struts 28 in this mannerprovides for a stronger and more durable attachment of the skirt to theframe. The inner skirt 16 can also be secured to the first, second,and/or third rows of struts 22, 24, and 26, respectively, with sutures70.

Due to the angled orientation of the fibers relative to the upper andlower edges, the skirt can undergo greater elongation in the axialdirection (i.e., in a direction from the upper edge 82 to the lower edge84). Thus, when the metal frame 12 is crimped, the inner skirt 16 canelongate in the axial direction along with the frame and thereforeprovide a more uniform and predictable crimping profile. Each cell ofthe metal frame in the illustrated embodiment includes at least fourangled struts that rotate towards the axial direction on crimping (e.g.,the angled struts become more aligned with the length of the frame). Theangled struts of each cell function as a mechanism for rotating thefibers of the skirt in the same direction of the struts, allowing theskirt to elongate along the length of the struts. This allows forgreater elongation of the skirt and avoids undesirable deformation ofthe struts when the prosthetic valve is crimped.

In addition, the spacing between the woven fibers or yarns can beincreased to facilitate elongation of the skirt in the axial direction.For example, for a PET inner skirt 16 formed from 20-denier yarn, theyarn density can be about 15% to about 30% lower than in a typical PETskirt. In some examples, the yarn spacing of the inner skirt 16 can befrom about 60 yarns per cm (about 155 yarns per inch) to about 70 yarnsper cm (about 180 yarns per inch), such as about 63 yarns per cm (about160 yarns per inch), whereas in a typical PET skirt the yarn spacing canbe from about 85 yarns per cm (about 217 yarns per inch) to about 97yarns per cm (about 247 yarns per inch). The oblique edges 86, 88promote a uniform and even distribution of the fabric material alonginner circumference of the frame during crimping so as to reduce orminimize bunching of the fabric to facilitate uniform crimping to thesmallest possible diameter. Additionally, cutting diagonal sutures in avertical manner may leave loose fringes along the cut edges. The obliqueedges 86, 88 help minimize this from occurring. Compared to theconstruction of a typical skirt (fibers running perpendicularly to theupper and lower edges of the skirt), the construction of the inner skirt16 avoids undesirable deformation of the frame struts and provides moreuniform crimping of the frame.

In alternative embodiments, the skirt can be formed from woven elasticfibers that can stretch in the axial direction during crimping of theprosthetic valve. The warp and weft fibers can run perpendicularly andparallel to the upper and lower edges of the skirt, or alternatively,they can extend at angles between 0 and 90 degrees relative to the upperand lower edges of the skirt, as described above.

The inner skirt 16 can be sutured to the frame 12 at locations away fromthe suture line 154 so that the skirt can be more pliable in that area.This configuration can avoid stress concentrations at the suture line154, which attaches the lower edges of the leaflets to the inner skirt16.

As noted above, the leaflet structure 14 in the illustrated embodimentincludes three flexible leaflets 40 (although a greater or a smallernumber of leaflets can be used). Additional information regarding theleaflets, as well as additional information regarding skirt material,can be found, for example, in U.S. patent application Ser. No.14/704,861, filed May 5, 2015, which is incorporated by reference in itsentirety.

The leaflets 40 can be secured to one another at their adjacent sides toform commissures 122 of the leaflet structure (FIG. 20). A plurality offlexible connectors 124 (one of which is shown in FIG. 16) can be usedto interconnect pairs of adjacent sides of the leaflets and to mount theleaflets to the commissure window frame portions 30 (FIG. 5). FIG. 16shows the adjacent sides of two leaflets 40 interconnected by a flexibleconnector 124. Three leaflets 40 can be secured to each otherside-to-side using three flexible connectors 124, as shown in FIG. 17.Additional information regarding connecting the leaflets to each other,as well as connecting the leaflets to the frame, can be found, forexample, in U.S. Patent Application Publication No. 2012/0123529, whichis incorporated by reference herein in its entirety.

As noted above, the inner skirt 16 can be used to assist in suturing theleaflet structure 14 to the frame. The inner skirt 16 can have anundulating temporary marking suture to guide the attachment of the loweredges of each leaflet 40. The inner skirt 16 itself can be sutured tothe struts of the frame 12 using sutures 70, as noted above, beforesecuring the leaflet structure 14 to the skirt 16. The struts thatintersect the marking suture desirably are not attached to the innerskirt 16. This allows the inner skirt 16 to be more pliable in the areasnot secured to the frame and minimizes stress concentrations along thesuture line that secures the lower edges of the leaflets to the skirt.As noted above, when the skirt is secured to the frame, the fibers 78,80 of the skirt (see FIG. 12) generally align with the angled struts ofthe frame to promote uniform crimping and expansion of the frame.

FIG. 18 shows one specific approach for securing the commissure portions122 of the leaflet structure 14 to the commissure window frame portions30 of the frame. The flexible connector 124 (FIG. 17) securing twoadjacent sides of two leaflets is folded widthwise and the upper tabportions 112 are folded downwardly against the flexible connector. Eachupper tab portion 112 is creased lengthwise (vertically) to assume anL-shape having a first portion 142 folded against a surface of theleaflet and a second portion 144 folded against the connector 124. Thesecond portion 144 can then be sutured to the connector 124 along asuture line 146. Next, the commissure tab assembly is inserted throughthe commissure window 20 of a corresponding window frame portion 30, andthe folds outside of the window frame portion 30 can be sutured toportions 144.

FIG. 18 also shows that the folded down upper tab portions 112 can forma double layer of leaflet material at the commissures. The firstportions 142 of the upper tab portions 112 are positioned flat againstlayers of the two leaflets 40 forming the commissures, such that eachcommissure comprises four layers of leaflet material just inside of thewindow frames 30. This four-layered portion of the commissures can bemore resistant to bending, or articulating, than the portion of theleaflets 40 just radially inward from the relatively more-rigidfour-layered portion. This causes the leaflets 40 to articulateprimarily at inner edges 143 of the folded-down first portions 142 inresponse to blood flowing through the prosthetic valve during operationwithin the body, as opposed to articulating about or proximal to theaxial struts of the window frames 30. Because the leaflets articulate ata location spaced radially inwardly from the window frames 30, theleaflets can avoid contact with and damage from the frame. However,under high forces, the four layered portion of the commissures can splayapart about a longitudinal axis adjacent to the window frame 30, witheach first portion 142 folding out against the respective second portion144. For example, this can occur when the prosthetic valve 10 iscompressed and mounted onto a delivery shaft, allowing for a smallercrimped diameter. The four-layered portion of the commissures can alsosplay apart about the longitudinal axis when the balloon catheter isinflated during expansion of the prosthetic valve, which can relievesome of the pressure on the commissures caused by the balloon, reducingpotential damage to the commissures during expansion.

After all three commissure tab assemblies are secured to respectivewindow frame portions 30, the lower edges of the leaflets 40 between thecommissure tab assemblies can be sutured to the inner skirt 16. Forexample, as shown in FIG. 19, each leaflet 40 can be sutured to theinner skirt 16 along suture line 154 using, for example, Ethibond Excel®PET thread. The sutures can be in-and-out sutures extending through eachleaflet 40, the inner skirt 16, and each reinforcing strip 72. Eachleaflet 40 and respective reinforcing strip 72 can be sewn separately tothe inner skirt 16. In this manner, the lower edges of the leaflets aresecured to the frame 12 via the inner skirt 16. As shown in FIG. 19, theleaflets can be further secured to the skirt with blanket sutures 156that extend through each reinforcing strip 72, leaflet 40 and the innerskirt 16 while looping around the edges of the reinforcing strips 72 andleaflets 40. The blanket sutures 156 can be formed from PTFE suturematerial. FIG. 20 shows a side view of the frame 12, leaflet structure14 and the inner skirt 16 after securing the leaflet structure 14 andthe inner skirt 16 to the frame 12 and the leaflet structure 14 to theinner skirt 16.

FIG. 21 is a flattened view of the outer skirt 18 prior to itsattachment to the frame 12, showing the outer surface of the skirt. FIG.22 is a flattened view of the outer skirt 18 prior to its attachment tothe frame 12, showing the inner surface of the skirt. FIG. 23 is aperspective view of the outer skirt prior to its attachment to the frame12. The outer skirt 18 can be laser cut or otherwise formed from astrong, durable material such as PET or various other suitable syntheticor natural materials configured to restrict and/or prevent blood-flowtherethrough. The outer skirt 18 can comprise a substantially straightlower (inflow or upstream) edge portion 160 and an upper (outflow ordownstream) edge portion 162 defining a plurality of alternatingprojections 164 and notches 166, or castellations, that generally followthe shape of a row of struts of the frame. The lower and upper edgeportions 160, 162 can have other shapes in alternative embodiments. Forexample, in one implementation, the lower edge portion 160 can be formedwith a plurality of projections generally conforming to the shape of arow of struts of the frame 12, while the upper edge portion 162 can bestraight.

In particular embodiments, the outer skirt 18 can comprise at least onesoft, plush surface 168 oriented radially outward so as to cushion andseal against native tissues surrounding the prosthetic valve. In certainexamples, the outer skirt 18 can be made from any of a variety of woven,knitted, or crocheted fabrics wherein the surface 168 is the surface ofa plush nap or pile of the fabric. Exemplary fabrics having a pileinclude velour, velvet, velveteen, corduroy, terrycloth, fleece, etc. Asbest shown in FIG. 23, the outer skirt can have a base layer 170 (afirst layer) from which a pile layer 172 (a second layer) extends. Thebase layer 170 can comprise warp and weft yarns woven or knitted into amesh-like structure. For example, in a representative configuration, theyarns of the base layer 170 can be flat yarns and can have a denierrange of from about 7 dtex to about 100 dtex, and can be knitted with adensity of from about 20 to about 100 wales per inch and from about 30to about 110 courses per inch. The yarns can be made from, for example,biocompatible thermoplastic polymers such as PET, PTFE(polytetrafluoroethylene), Nylon, etc., or any other suitable natural orsynthetic fibers.

The pile layer 172 can comprise pile yarns 174 woven or knitted intoloops. In certain configurations, the pile yarns 174 can be the warpyarns or the weft yarns of the base layer 170 woven or knitted to formthe loops. The pile yarns 174 can also be separate yarns incorporatedinto the base layer, depending upon the particular characteristicsdesired. In a representative configuration, the pile yarns 174 can beflat yarns and can have a denier range of from about 7 dtex to about 100dtex, and can be knitted with a density of from about 20 to about 100wales per inch and from about 30 to about 110 courses per inch. The pileyarns can be made from, for example, biocompatible thermoplasticpolymers such as PET, PTFE, Nylon, etc., or any other suitable naturalor synthetic fibers.

In certain embodiments, the loops can be cut such that the pile layer172 is a cut pile in the manner of, for example, a velour fabric. FIGS.1 and 21 illustrate a representative embodiment of the outer skirt 18configured as a velour fabric. In other embodiments, the loops can beleft intact to form a looped pile in the manner of, for example,terrycloth. FIG. 23 illustrates a representative embodiment of the outerskirt 18 in which the pile yarns 174 are knitted to form loops 176.

The height of the pile yarns 174 (e.g., the loops 176) can be the samefor all pile yarns across the entire extent of the outer skirt so as toprovide an outer skirt having a constant thickness. In alternativeembodiments, the height of the pile yarns 174 can vary along the heightand/or circumference of the outer skirt so as to vary the thickness ofthe outer skirt along its height and/or circumference, as furtherdescribed below.

The pile layer 172 has a much greater surface area than similarly sizedskirts formed from flat or woven materials, and therefore can enhancetissue ingrowth compared to known skirts. Promoting tissue growth intothe pile layer 172 can decrease perivaluvular leakage, increaseretention of the valve at the implant site and contribute to long-termstability of the valve. In some configurations, the surface area of thepile yarns 174 can be further increased by using textured yarns havingan increased surface area due to, for example, a wavy or undulatingstructure. In configurations such as the looped pile embodiment of FIG.23, the loop structure and the increased surface area provided by thetextured yarn of the loops 176 can allow the loops to act as a scaffoldfor tissue growth into and around the loops of the pile.

The outer skirt embodiments described herein can also contribute toimproved compressibility and shape memory properties of the outer skirtover known valve coverings and skirts. For example, the pile layer 172can be compliant such that it compresses under load (e.g., when incontact with tissue, other implants, or the like), and returns to itsoriginal size and shape when the load is relieved. This can help toimprove sealing between the outer skirt and the tissue of the nativeannulus, or a surrounding support structure in which the prostheticvalve is deployed. Embodiments of an implantable support structure thatis adapted to receive a prosthetic valve and retain it within the nativemitral valve are disclosed in co-pending Application No. 62/449,320,filed Jan. 23, 2017, and application Ser. No. 15/876,053, filed Jan. 19,2018, which are incorporated herein by reference. The compressibilityprovided by the pile layer 172 of the outer skirt 18 is also beneficialin reducing the crimp profile of the valve. Additionally, the outerskirt 18 can prevent the leaflets 40 or portions thereof from extendingthrough spaces between the struts of the frame 12 as the prostheticvalve is crimped, thereby protecting against damage to the leaflets dueto pinching of the leaflets between struts.

In alternative embodiments, the outer skirt 18 be made of a non-wovenfabric such as felt, or fibers such as non-woven cotton fibers. Theouter skirt 18 can also be made of porous or spongey materials such as,for example, any of a variety of compliant polymeric foam materials, orwoven fabrics, such as woven PET.

Various techniques and configurations can be used to secure the outerskirt 18 to the frame 12 and/or the inner skirt 16. As best shown inFIG. 3, a lower edge portion 180 of the inner skirt 16 can be wrappedaround the inflow end 15 of the frame 12, and the lower edge portion 160of the outer skirt 18 can be attached to the lower edge portion 180 ofthe inner skirt 16 and/or the frame 12, such as with one or more suturesor stitches 182 (as best shown in FIG. 2) and/or an adhesive. In lieu ofor in addition to sutures, the outer skirt 18 can be attached to theinner skirt 16, for example, by ultrasonic welding. In the illustratedembodiment, the lower edge portion 160 of the outer skirt 18 can be freeof loops, and the lower edge portion 180 of the inner skirt 16 canoverlap and can be secured to the base layer 170 of the outer skirt 18.In other embodiments, the lower edge portion 180 of the inner skirt 16can extend over one or more rows of loops 176 of the pile layer 172 (seeFIG. 27), as further described below. In other embodiments, the loweredge portion 180 of the inner skirt 18 can be wrapped around the inflowend of the frame and extend between the outer surface of the frame andthe outer skirt 18 (i.e., the outer skirt 18 is radially outward of thelower edge portion 180 of the inner skirt 18).

As shown in FIG. 1, each projection 164 of the outer skirt 18 can beattached to the third row III of struts 26 (FIG. 5) of the frame 12. Theprojections 164 can, for example, be wrapped over respective struts 26of row III and secured with sutures 184. The outer skirt 18 can befurther secured to the frame 12 by suturing an intermediate portion ofthe outer skirt (a portion between the lower and upper edge portions) tostruts of the frame, such as struts 24 of the second row II of struts.

The height of the outer skirt (as measured from the lower edge to theupper edge) can vary in alternative embodiments. For example, in someembodiments, the outer skirt can cover the entire outer surface of theframe 12, with the lower edge portion 160 secured to the inflow end ofthe frame 12 and the upper edge portion secured to the outflow end ofthe frame. In another embodiment, the outer skirt 18 can extend from theinflow end of the frame to the second row II of struts 24, or to thefourth row IV of struts 28, or to a location along the frame between tworows of struts. In still other embodiments, the outer skirt 18 need notextend all the way to the inflow end of the frame, and instead theinflow end of the outer skirt can secured to another location on theframe, such as to the second row II of struts 24.

The outer skirt 18 desirably is sized and shaped relative to the framesuch that when the prosthetic valve 10 is in its radially expandedstate, the outer skirt 18 fits snugly (in a tight-fitting manner)against the outer surface of the frame. When the prosthetic valve 10 isradially compressed to a compressed state for delivery, the portion ofthe frame on which the outer skirt is mounted can elongate axially. Theouter skirt 18 desirably has sufficient elasticity to stretch in theaxial direction upon radial compression of the frame so that it does notto prevent full radial compression of the frame or deform the strutsduring the crimping process.

Known skirts that have material slack or folds when the prosthetic valveis expanded to its functional size are difficult to assemble because thematerial must be adjusted as it is sutured to the frame. In contrast,because the outer skirt 18 is sized to fit snugly around the frame inits fully expanded state, the assembly process of securing the skirt tothe frame is greatly simplified. During the assembly process, the outerskirt can be placed around the frame with the frame in its fullyexpanded state and the outer skirt in its final shape and position whenthe valve is fully functional. In this position, the skirt can then besutured to the frame and/or the inner skirt. This simplifies thesuturing process compared to skirts that are designed to have slack orfolds when radially expanded.

As shown in FIG. 3, the height of the loops of the pile layer 172 can beconstant across the entire extent of the outer skirt such that the outerskirt 18 has a constant thickness, except along the upper and lower edgeportions which can be free of loops to facilitate attachment of theouter skirt to the frame and/or the inner skirt 16. The “height” of theloops is measured in the radial direction when the skirt is mounted onthe frame. In another embodiment, as shown in FIG. 24, the loops cancomprise lower loops 176 a along the lower or upstream portion of theskirt that are relatively shorter in height (as represented by a thinnercross-sectional area) than upper loops 176 b (as represented by athicker cross-sectional area) along the upper or downstream portion ofthe skirt. The skirt 18 can further include a group of intermediateloops 176 c that gradually increase in height from the lower loops 176 ato the upper loops 176 b. Thus, in the embodiment of FIG. 24, thethickness of outer skirt 18 increases from a minimum thickness along thelower portion to a maximum thickness along the upper portion.

FIG. 25 shows another embodiment in which the loops of the outer skirtcomprise lower loops 176 d along the lower portion of the skirt that arerelatively higher or longer in height than upper loops 176 e along theupper portion of the skirt. The skirt 18 can further include a group ofintermediate loops 176 f that gradually decrease in height from thelower loops 176 d to the upper loops 176 e. Thus, in the embodiment ofFIG. 25, the thickness of outer skirt 18 decreases from a maximumthickness along the lower portion to a minimum thickness along the upperportion.

FIG. 26 shows another embodiment in which the loops comprise lower loops176 g, upper loops 176 h, and intermediate loops 176 i that are relativeshorter in height than the lower and upper loops. As shown, the lowerloops 176 g can gradually decrease in height from the lower edge of theskirt toward the intermediate loops 176 i, and the upper loops 176 h cangradually decrease in height from the upper edge of the skirt toward theintermediate loops 176 i. Thus, in the embodiment of FIG. 26, thethickness of the outer skirt decreases from a maximum thickness alongthe lower portion to a minimum thickness along the intermediate portion,and then increases from the intermediate portion to the maximumthickness along the upper portion. In the illustrated embodiment, theupper portion of the skirt containing the upper loops 176 h has the samethickness as the lower portion of the skirt containing the lower loops176 g. In other embodiments, the thickness of the upper portion of theskirt containing the upper loops 176 h can be greater or less than thesame thickness of the lower portion of the skirt containing the lowerloops 176 g.

Further, in any of the embodiments described above where the height ofthe loops vary along the height of the skirt, the height of the loopsneed not vary gradually from one section of the skirt to another sectionof the skirt. Thus, an outer skirt can have loops of different heights,wherein the height of the loops change abruptly at locations along theskirt. For example, in the embodiment of FIG. 24, the lower portion ofthe skirt containing the lower loops 176 a can extend all the way to theupper portion of the skirt containing the upper loops 176 g without theintermediate loops 176 c forming a transition between the upper andlower portions.

In lieu of or in addition to having loops that vary in height along theheight of the skirt, the height of the loops 176 (and therefore thethickness of the outer skirt) can vary along the circumference of theouter skirt. For example, the height of the loops can be increased alongcircumferential sections of the skirt where larger gaps might beexpected between the outer skirt and the native annulus, such ascircumferential sections of the skirt that are aligned with thecommissures of the native valve.

FIGS. 27 and 28 show an alternative configuration for mounting the outerskirt 18 to the frame 12. In this embodiment, as best shown in FIG. 27,the lower edge portion 180 of the inner skirt 16 is wrapped around theinflow end of the frame and extended over one or more rows of loopsalong the lower edge portion 160 of the outer skirt. The lower edgeportion 180 of the inner skirt 16 can then be secured to the lower edgeportion 160 of the outer skirt, such as with sutures or stitching 186(FIG. 28), an adhesive, and/or welding (e.g., ultrasonic welding). Thestitching 186 can also extend around selected struts adjacent the inflowend of the frame. The lower edge portion 180 of the inner skirt iseffective to partially compress the loops of the pile layer 172, whichcreates a tapered edge at the inflow end of the prosthetic valve. Thetapered edge reduces the insertion force required to push the prostheticvalve through an introducer sheath when being inserted into a patient'sbody. In one specific implementation, the stitching 186 secures thelower edge portion 180 of the inner skirt to the outer skirt 18 at adistance of at least 1 mm from the lowermost edge of the outer skirt.The upper edge portion 162 and the intermediate portion of the outerskirt can then be secured to the frame as previously described.

FIGS. 29-32 show another configuration for mounting the outer skirt 18to the frame 12. In this embodiment, the outer skirt 18 is initiallyplaced in a tubular configuration with the base layer 170 facingoutwardly and the lower edge portion 160 (which can be free of loops176) can be placed between the inner surface of the frame 12 and thelower edge portion 180 of the inner skirt 16, as depicted in FIG. 30.The lower edge portions of the outer skirt and the inner skirt can besecured to each other, such as with stitches, an adhesive, and/orwelding (e.g., ultrasonic welding). In one implementation, the loweredge portions of the outer skirt and the inner skirt are secured to eachother with in-and-out stitches and locking stitches. The outer skirt 18is then inverted and pulled upwardly around the outer surface of theframe 12 such that the base layer 170 is placed against the outersurface of the frame and the pile layer 172 faces outwardly, as depictedin FIG. 29. In this assembled configuration, the lower edge portion 160of the outer skirt wraps around the inflow end of the frame and issecured to the inner skirt inside of the frame. The upper edge portion162 and the intermediate portion of the outer skirt can then be securedto the frame as previously described.

The prosthetic valve 10 can be configured for and mounted on a suitabledelivery apparatus for implantation in a subject. Several catheter-baseddelivery apparatuses are known; a non-limiting example of a suitablecatheter-based delivery apparatus includes that disclosed in U.S. PatentApplication Publication No. 2013/0030519, which is incorporated byreference herein in its entirety, and U.S. Patent ApplicationPublication No. 2012/0123529.

To implant a plastically-expandable prosthetic valve 10 within apatient, the prosthetic valve 10 including the outer skirt 18 can becrimped on an elongated shaft of a delivery apparatus. The prostheticvalve, together with the delivery apparatus, can form a deliveryassembly for implanting the prosthetic valve 10 in a patient's body. Theshaft can comprise an inflatable balloon for expanding the prostheticvalve within the body. With the balloon deflated, the prosthetic valve10 can then be percutaneously delivered to a desired implantationlocation (e.g., a native aortic valve region). Once the prosthetic valve10 is delivered to the implantation site (e.g., the native aortic valve)inside the body, the prosthetic valve 10 can be radially expanded to itsfunctional state by inflating the balloon or equivalent expansionmechanism.

The outer skirt 18 can fill-in gaps between the frame 12 and thesurrounding native annulus to assist in forming a good, fluid-tight sealbetween the prosthetic valve 10 and the native annulus. The outer skirt18 therefore cooperates with the inner skirt 16 to avoid perivalvularleakage after implantation of the prosthetic valve 10. Additionally, asdiscussed above, the pile layer of the outer skirt further enhancesperivalvular sealing by promoting tissue ingrowth with the surroundingtissue.

Alternatively, a self-expanding prosthetic valve 10 can be crimped to aradially collapsed configuration and restrained in the collapsedconfiguration by inserting the prosthetic valve 10, including the outerskirt 18, into a sheath or equivalent mechanism of a delivery catheter.The prosthetic valve 10 can then be percutaneously delivered to adesired implantation location. Once inside the body, the prostheticvalve 10 can be advanced from the delivery sheath, which allows theprosthetic valve to expand to its functional state.

FIG. 33 illustrates a sealing member 200 for a prosthetic valve,according to another embodiment. The sealing member 200 in theillustrated embodiment is formed from a spacer fabric. The sealingmember 200 can be positioned around the outer surface of the frame 12 ofa prosthetic valve (in place of the outer skirt 18) and secured to theinner skirt 16 and/or the frame using stitching, an adhesive, and/orwelding (e.g., ultrasonic welding).

As best shown in FIG. 34, the spacer fabric can comprise a first, innerlayer 206, a second, outer layer 208, and an intermediate spacer layer210 extending between the first and second layers to create athree-dimensional fabric. The first and second layers 206, 208 can bewoven fabric or mesh layers. In certain configurations, one or more ofthe first and second layers 206, 208 can be woven such that they definea plurality of openings 212. In some examples, openings such as theopenings 212 can promote tissue growth into the sealing member 200. Inother embodiments, the layers 206, 208 need not define openings, but canbe porous, as desired.

The spacer layer 210 can comprise a plurality of pile yarns 214. Thepile yarns 214 can be, for example, monofilament yarns arranged to forma scaffold-like structure between the first and second layers 206, 208.For example, FIGS. 34 and 35 illustrate an embodiment in which the pileyarns 214 extend between the first and second layers 206, 208 in asinusoidal or looping pattern.

In certain examples, the pile yarns 214 can have a rigidity that isgreater than the rigidity of the fabric of the first and second layers206, 208 such that the pile yarns 214 can extend between the first andsecond layers 206, 208 without collapsing under the weight of the secondlayer 208. The pile yarns 214 can also be sufficiently resilient suchthat the pile yarns can bend or give when subjected to a load, allowingthe fabric to compress, and return to their non-deflected state when theload is removed. For example, when the prosthetic valve is radiallycompressed for delivery into a patient's body and placed in a deliverysheath of a delivery apparatus or advanced through an introducer sheath,the pile yarns 214 can compress to reduce the overall crimp profile ofthe prosthetic valve, and then return to their non-deflected state whendeployed from the delivery sheath or the introducer sheath, as the casemay be.

The spacer fabric can be warp-knitted, or weft-knitted, as desired. Someconfigurations of the spacer cloth can be made on a double-bar knittingmachine. In a representative example, the yarns of the first and secondlayers 206, 208 can have a denier range of from about 10 dtex to about70 dtex, and the yarns of the monofilament pile yarns 214 can have adenier range of from about 2 mil to about 10 mil. The pile yarns 214 canhave a knitting density of from about 20 to about 100 wales per inch,and from about 30 to about 110 courses per inch. Additionally, in someconfigurations (e.g., warp-knitted spacer fabrics) materials withdifferent flexibility properties may be incorporated into the spacercloth to improve the overall flexibility of the spacer cloth.

FIG. 36 shows an outer sealing member 18′ mounted on the outside of theframe 12 of a prosthetic heart valve 10, according to anotherembodiment. FIG. 37 shows the base layer 170 of the sealing member 18′in a flattened configuration. FIG. 38 shows the pile layer 172 of thesealing member 18′ in a flattened configuration. The outer sealingmember 18′ is similar to the sealing member 18 of FIGS. 1 and 21-23,except that the height (H₁) of the base layer 170 is greater than theheight (H₂) of the pile layer 172 Like the previously describedembodiments, the sealing member 18′ desirably is sized and shapedrelative to the frame 12 such that when the prosthetic valve is in itsradially expanded state, both layers 170, 172 of the sealing member 18fit snugly (in a tight-fitting manner) around the outer surface of theframe.

In the illustrated configuration, the base layer 170 extends axiallyfrom the inlet end of the frame 12 to the third row III of struts 26 ofthe frame 12. The upstream and downstream edges of the base layer 170can be sutured to the struts 22 of the first row I and to the struts 26of the third row III with sutures 182 and 184, respectively, aspreviously described. The pile layer 172 in the illustratedconfiguration extends from the inlet end of the frame 12 to a plane thatintersects the frame at the nodes formed at the intersection of theupper ends of struts 24 of the second row II and the lower ends ofstruts 26 of the third row III, wherein the plane is perpendicular tothe central axis of the frame.

The pile layer 172 can be separately formed from and subsequentlyattached to the base layer 170, such as with sutures, an adhesive,and/or welding. Alternatively, the pile layer 172 can be formed fromyarns or fibers woven into the base layer 170. The pile layer 172 canhave any of the configurations shown in FIGS. 24-26.

In particular embodiments, the height H₁ of the base layer 170 can beabout 9 mm to about 25 mm or about 13 mm to about 20 mm, with about 19mm being a specific example. The height H₂ of the pile layer 172 can beat least 2 mm less than H₁, at least 3 mm less than H₁, at least 4 mmless than H₁, at least 5 mm less than H₁, at least 6 mm less than H₁, atleast 7 mm less than H₁, at least 8 mm less than H₁, at least 9 mm thanH₁, or at least 10 mm less than H₁. The height of the frame 12 in theradially expanded state can be about 12 mm to about 27 mm or about 15 mmto about 23 mm, with about 20 mm being a specific example.

The relatively shorter pile layer 172 reduces the crimp profile alongthe mid-section of the prosthetic valve 10 but still provides forenhanced paravalvular sealing along the majority of the landing zone ofthe prosthetic valve. The base layer 170 also provides a sealingfunction downstream of the downstream edge of the pile layer 172.

FIGS. 39-40 show an outer sealing member 300 for a prosthetic heartvalve (e.g., a prosthetic heart valve 10), according to anotherembodiment. FIGS. 39A and 40A are magnified views of portions of thesealing member shown in FIGS. 39 and 40, respectively. The sealingmember 300 can be mounted on the outside of the frame 12 of a prostheticvalve 10 in lieu of sealing member 18 using, for example, sutures,ultrasonic welding, or any other suitable attachment method. Like thepreviously described embodiments, the sealing member 300 desirably issized and shaped relative to the frame 12 such that when the prostheticvalve is in its radially expanded state, the sealing member 300 fitssnugly (in a tight-fitting manner) against the outer surface of theframe.

The sealing member 300, like sealing members 18, 18′, can be adual-layer fabric comprising a base layer 302 and a pile layer 304. FIG.39 shows the outer surface of the sealing member 300 defined by the pilelayer 304. FIG. 40 shows the inner surface of the sealing member 300defined by the base layer 302. The base layer 302 in the illustratedconfiguration comprises a mesh weave having circumferentially extendingrows or stripes 306 of higher-density mesh portions interspersed withrows or stripes 308 of lower-density mesh portions.

In particular embodiments, the yarn count of yarns extending in thecircumferential direction (side-to-side or horizontally in FIGS. 40 and40A) is greater in the higher-density rows 306 than in the lower-densityrows 308. In other embodiments, the yarn count of yarns extending in thecircumferential direction and the yarn count of yarns extending in theaxial direction (vertically in FIGS. 40 and 40A) is greater in thehigher-density rows 306 than in the lower-density rows 308.

The pile layer 304 can be formed from yarns woven into the base layer302. For example, the pile layer 304 can comprise a velour weave formedfrom yarns incorporated in the base layer 302. The pile layer 304 cancomprise circumferentially extending rows or stripes 310 of pile formedat axially-spaced locations along the height of the sealing member 300such that there are axial extending gaps between adjacent rows 310. Inthis manner, the density of the pile layer varies along the height ofthe sealing member. In alternative embodiments, the pile layer 304 canbe formed without gaps between adjacent rows of pile, but the pile layercan comprise circumferentially extending rows or stripes ofhigher-density pile interspersed with rows or stripes 312 oflower-density pile.

In alternative embodiments, the base layer 302 can comprise a uniformmesh weave (the density of the weave pattern is uniform) and the pilelayer 304 has a varying density.

Varying the density of the pile layer 304 and/or the base layer 302along the height of the sealing member 300 is advantageous in that itfacilitates axially elongation of the sealing member 300 caused by axialelongation of the frame 12 when the prosthetic heart valve is crimped toa radially compressed state for delivery. The varying density alsoreduces the bulkiness of the sealing member in the radially collapsedstate and therefore reduces the overall crimp profile of the prostheticheart valve.

In alternative embodiments, the density of the sealing member 300 canvary along the circumference of the sealing member to reduce thebulkiness of the sealing member in the radially collapsed state. Forexample, the pile layer 304 can comprise a plurality ofaxially-extending, circumferentially-spaced, rows of pile yarns, oralternatively, alternating axially-extending rows of higher-density pileinterspersed with axially-extending rows of lower-density pile.Similarly, the base layer 302 can comprise a plurality axially-extendingrows of higher-density mesh interspersed with rows of lower-densitymesh.

In other embodiments, the sealing member 300 can include a base layer302 and/or a pile layer 304 that varies in density along thecircumference of the sealing member and along the height of the sealingmember.

In other embodiments, a sealing member can be knitted, crocheted, orwoven to have rows or sections of higher stitch density and rows orsections of lower stitch density without two distinct layers. FIG. 41,for example, shows a sealing member 400 comprising a fabric having aplurality of axially-extending rows 402 of higher-density stitchingalternating with axially-extending rows 404 of lower-density stitching.The sealing member 400 can be formed, for example, by knitting,crocheting, or weaving a single layer fabric having rows 402, 404 formedby increasing the stitch density along the rows 402 and decreasing thestitch density along the rows 404 while the fabric is formed. Thesealing member 400 can be mounted on the outside of the frame 12 of aprosthetic valve 10 in lieu of sealing member 18 using, for example,sutures, ultrasonic welding, or any other suitable attachment method.Like the previously described embodiments, the sealing member 400desirably is sized and shaped relative to the frame 12 such that whenthe prosthetic valve is in its radially expanded state, the sealingmember 400 fits snugly (in a tight-fitting manner) against the outersurface of the frame.

The sealing member 400 can be resiliently stretchable between a first,substantially relaxed, axially foreshortened configuration (FIG. 41)corresponding to a radially expanded state of the prosthetic valve, anda second, axially elongated, or tensioned configuration (FIG. 42)corresponding to a radially compressed state of the prosthetic valve. Asshown in FIG. 41, when the prosthetic valve is radially expanded and thesealing member 400 is in the first configuration, the higher-densityrows 402 extend in an undulating pattern from the lower (upstream edge)to the upper (downstream edge) of the sealing member 400. In theillustrated embodiment, for example, each of the higher-density rows 402comprises a plurality of straight angled sections 406 a, 406 b arrangedend-to-end in a zig-zag or herringbone pattern extending from the lower(upstream edge) to the upper (downstream edge) of the sealing member400. In alternative embodiments, the rows 402 can be sinusoidal-shapedrows having curved longitudinal edges.

When the prosthetic valve is crimped to its radially compressed state,the frame 12 elongates, causing the sealing member to stretch in theaxial direction, as depicted in FIG. 42, to its second configuration.The lower-density rows 404 facilitate elongation of the sealing memberand permit straightening of the higher-density rows 402. FIG. 42 depictsthe higher-density rows 402 as straight sections extending from theinflow edge to the outflow edge of the sealing member. However, itshould be understood that the higher-density rows 402 need not formperfectly straight rows when the prosthetic valve is in the radiallycompressed state. Instead, “straightening” of the higher-density rows402 occurs when the angle 408 between adjacent angled segments 406 a,406 b of each row increases upon axial elongation of the sealing member.

The varying stitch density of the sealing member 400 reduces overallbulkiness of the sealing member to minimize the crimp profile of theprosthetic valve. The zig-zag or undulating pattern of thehigher-density rows 402 in the radially expanded state of the prostheticvalve facilitates stretching of the sealing member in the axialdirection upon radial compression of the prosthetic valve and allows thesealing member to return to its pre-stretched state in which the sealingmember fits snugly around the frame upon radial expansion of theprosthetic valve. Additionally, the zig-zag or undulating pattern of thehigher-density rows 402 in the radially expanded state of the prostheticvalve eliminates any straight flow paths for blood between adjacent rows402 extending along the outer surface of the sealing member from itsoutflow edge to its inflow edge to facilitate sealing and tissueingrowth with surrounding tissue.

In alternative embodiments, a sealing member 400 can have a plurality ofcircumferentially extending higher-density rows (like rows 402 butextending in the circumferential direction) interspersed with aplurality of circumferentially extending lower-density rows (like rows404 but extending in the circumferential direction). In someembodiments, a sealing member 400 can have axially-extending andcircumferential-extending higher-density rows interspersed withaxially-extending and circumferential-extending lower-density rows.

FIGS. 43A, 43B, 44A, and 44B illustrate an outer sealing member 500 fora prosthetic heart valve (e.g., a prosthetic heart valve 10), accordingto another embodiment. The sealing member 500 can have a plush exteriorsurface 504. The sealing member 500 can be secured to a frame 12 of theprosthetic valve using, for example, sutures, ultrasonic welding, or anyother suitable attachment method as previously described herein. Forpurposes of illustration, enlarged or magnified portions of the sealingmember 500 are shown in the figures. It should be understood that theoverall size and shape of the sealing member 500 can be modified asneeded to cover the entire outer surface of the frame 12 or portion ofthe outer surface of the frame, as previously described herein.

The sealing member 500 can comprise a woven or knitted fabric. Thefabric can be resiliently stretchable between a first, natural, orrelaxed configuration (FIG. 43A), and a second, axially elongated, ortensioned configuration (FIG. 43B). When disposed on the frame 12, therelaxed configuration can correspond to the radially expanded,functional configuration of the prosthetic valve, and the elongatedconfiguration can correspond to the radially collapsed deliveryconfiguration of the prosthetic valve. Thus, with reference to FIG. 43A,the sealing member 500 can have a first length L₁ in the axial directionwhen the prosthetic valve is in the radially expanded configuration, anda second length L₂ (FIG. 43B) in the axial direction that is longer thanL₁ when the valve is crimped to the delivery configuration, as describedin greater detail below.

The fabric can comprise a plurality of circumferentially extending warpyarns 512 and a plurality of axially extending weft yarns 514. In someembodiments, the warp yarns 512 can have a denier of from about 1 D toabout 300 D, about 10 D to about 200 D, or about 10 D to about 100 D. Insome embodiments, the warp yarns 512 can have a thickness t₁ (FIG. 44A)of from about 0.01 mm to about 0.5 mm, about 0.02 mm to about 0.3 mm, orabout 0.03 mm to about 0.1 mm. In some embodiments, the warp yarns 512can have a thickness t₁ of about 0.03 mm, about 0.04 mm, about 0.05 mm,about 0.06 mm, about 0.07 mm, about 0.08 mm, about 0.09 mm, or about 0.1mm. In a representative embodiment, the warp yarns 512 can have athickness of about 0.06 mm.

The weft yarns 514 can be texturized yarns comprising a plurality oftexturized filaments 516. For example, the filaments 516 of the weftyarns 514 can be bulked, wherein, for example, the filaments 516 aretwisted, heat set, and untwisted such that the filaments retain theirdeformed, twisted shape in the relaxed, non-stretched configuration. Thefilaments 516 can also be texturized by crimping, coiling, etc. When theweft yarns 514 are in a relaxed, non-tensioned state, the filaments 516can be loosely packed and can provide compressible volume or bulk to thefabric, as well as a plush surface. In some embodiments, the weft yarns514 can have a denier of from about 1 D to about 500 D, about 10 D toabout 400 D, about 20 D to about 350 D, about 20 D to about 300 D, orabout 40 D to about 200 D. In certain embodiments, the weft yarns 514can have a denier of about 150 D. In some embodiments, a filament countof the weft yarns 514 can be from 2 filaments per yarn to 200 filamentsper yarn, 10 filaments per yarn to 100 filaments per yarn, 20 filamentsper yarn to 80 filaments per yarn, or about 30 filaments per yarn to 60filaments per yarn. Additionally, although the axially-extendingtextured yarns 514 are referred to as weft yarns in the illustratedconfiguration, the fabric may also be manufactured such that theaxially-extending textured yarns are warp yarns and thecircumferentially-extending yarns are weft yarns.

FIGS. 44A and 44B illustrate a cross-sectional view of the sealingmember in which the weft yarns 512 extend into the plane of the page.With reference to FIG. 44A, the fabric of the sealing member 500 canhave a thickness t₂ of from about 0.1 mm to about 10 mm, about 1 mm toabout 8 mm, about 1 mm to about 5 mm, about 1 mm to about 3 mm, about0.5 mm, about 1 mm, about 1.5 mm, about 2 mm, about 2.5 mm, or about 3mm when in a relaxed state and secured to a frame. In some embodiments,the sealing member 500 can have a thickness of about 0.1 mm, about 0.2mm, about 0.3 mm, about 0.4 mm, or about 0.5 mm as measured in a relaxedstate with a weighted drop gauge having a presser foot. In arepresentative example, the sealing member can have a thickness of about1.5 mm when secured to a prosthetic valve frame in the relaxed state.The texturized, loosely packed filaments 516 of the weft yarns 514 inthe relaxed state can also promote tissue growth into the sealing member500.

When the fabric is in the relaxed state, the textured filaments 516 ofthe weft yarns 514 can be widely dispersed such that individual weftyarns are not readily discerned, as depicted in FIG. 43A. When tensionedin the axial direction, the filaments 516 of the weft yarns 514 can bedrawn together as the weft yarns elongate and the kinks, twists, etc.,of the filaments are pulled straight such that the fabric is stretchedand the thickness decreases. In certain embodiments, when sufficienttension is applied to the fabric in the axial direction (the weftdirection in the illustrated embodiment), such as when the prostheticvalve is crimped onto a shaft of a delivery apparatus, the texturedfibers 516 can be pulled together such that individual weft yarns 514become discernable, as best shown in FIG. 43B.

Thus, for example, when fully stretched, the sealing member can have asecond thickness t₃, as shown in FIG. 44B that is less than thethickness t₂. In certain embodiments, the thickness of the tensionedweft yarns 514 may be the same or nearly the same as the thickness t₁ ofthe warp yarns 512. Thus, in certain examples, when stretched the fabriccan have a thickness t₃ that is the same or nearly the same as threetimes the thickness t₁ of the warp yarns 512 depending upon, forexample, the amount of flattening of the weft yarns 514. Accordingly, inthe example above in which the warp yarns 512 have a thickness of about0.06 mm, the thickness of the sealing member can vary between about 0.2mm and about 1.5 mm as the fabric stretches and relaxes. Stateddifferently, the thickness of the fabric can vary by 750% or more as thefabric stretches and relaxes.

Additionally, as shown in FIG. 44A, the warp yarns 512 can be spacedapart from each other in the fabric by a distance y₁ when the outercovering is in a relaxed state. As shown in FIGS. 43B and 44B, whentension is applied to the fabric in the direction perpendicular to thewarp yarns 512 and parallel to the weft yarns 514, the distance betweenthe warp yarns 512 can increase as the weft yarns 514 lengthen. In theexample illustrated in FIG. 44B, in which the fabric has been stretchedsuch that the weft yarns 514 have lengthened and narrowed toapproximately the diameter of the warp yarns 512, the distance betweenthe warp yarns 512 can increase to a new distance y₂ that is greaterthan the distance y₁.

In certain embodiments, the distance y₁ can be, for example, about 1 mmto about 10 mm, about 2 mm to about 8 mm, or about 3 mm to about 5 mm.In a representative example, the distance y₁ can be about 3 mm. In someembodiments, when the fabric is stretched as in FIGS. 43B and 44B, thedistance y₂ can be about 6 mm to about 10 mm. Thus, in certainembodiments, the length of the sealing member 500 in the axial directioncan vary by 100% or more between the relaxed length L₁ and the fullystretched length (e.g., L₂). The fabric's ability to lengthen in thismanner facilitates crimping of the prosthetic valve. Thus, the sealingmember 500 can be soft and voluminous when the prosthetic valve isexpanded to its functional size, and relatively thin when the prostheticvalve is crimped to minimize the overall crimp profile of the prostheticvalve.

General Considerations

It should be understood that the disclosed embodiments can be adapted todeliver and implant prosthetic devices in any of the native annuluses ofthe heart (e.g., the pulmonary, mitral, and tricuspid annuluses), andcan be used with any of various approaches (e.g., retrograde, antegrade,transseptal, transventricular, transatrial, etc.). The disclosedembodiments can also be used to implant prostheses in other lumens ofthe body. Further, in addition to prosthetic valves, the deliveryassembly embodiments described herein can be adapted to deliver andimplant various other prosthetic devices such as stents and/or otherprosthetic repair devices.

For purposes of this description, certain aspects, advantages, and novelfeatures of the embodiments of this disclosure are described herein. Thedisclosed methods, apparatus, and systems should not be construed asbeing limiting in any way. Instead, the present disclosure is directedtoward all novel and nonobvious features and aspects of the variousdisclosed embodiments, alone and in various combinations andsub-combinations with one another. The methods, apparatus, and systemsare not limited to any specific aspect or feature or combinationthereof, nor do the disclosed embodiments require that any one or morespecific advantages be present or problems be solved.

Although the operations of some of the disclosed embodiments aredescribed in a particular, sequential order for convenient presentation,it should be understood that this manner of description encompassesrearrangement, unless a particular ordering is required by specificlanguage set forth below. For example, operations described sequentiallymay in some cases be rearranged or performed concurrently. Moreover, forthe sake of simplicity, the attached figures may not show the variousways in which the disclosed methods can be used in conjunction withother methods. Additionally, the description sometimes uses terms like“provide” or “achieve” to describe the disclosed methods. These termsare high-level abstractions of the actual operations that are performed.The actual operations that correspond to these terms may vary dependingon the particular implementation and are readily discernible by one ofordinary skill in the art.

As used in this application and in the claims, the singular forms “a,”“an,” and “the” include the plural forms unless the context clearlydictates otherwise. Additionally, the term “includes” means “comprises.”Further, the terms “coupled” and “associated” generally meanelectrically, electromagnetically, and/or physically (e.g., mechanicallyor chemically) coupled or linked and does not exclude the presence ofintermediate elements between the coupled or associated items absentspecific contrary language.

As used herein, the term “proximal” refers to a position, direction, orportion of a device that is closer to the user and further away from theimplantation site. As used herein, the term “distal” refers to aposition, direction, or portion of a device that is further away fromthe user and closer to the implantation site. Thus, for example,proximal motion of a device is motion of the device toward the user,while distal motion of the device is motion of the device away from theuser. The terms “longitudinal” and “axial” refer to an axis extending inthe proximal and distal directions, unless otherwise expressly defined.

As used herein, the terms “integrally formed” and “unitary construction”refer to a construction that does not include any welds, fasteners, orother means for securing separately formed pieces of material to eachother.

As used herein, operations that occur “simultaneously” or “concurrently”occur generally at the same time as one another, although delays in theoccurrence of one operation relative to the other due to, for example,spacing, play or backlash between components in a mechanical linkagesuch as threads, gears, etc., are expressly within the scope of theabove terms, absent specific contrary language.

In view of the many possible embodiments to which the principles of thedisclosed invention may be applied, it should be recognized that theillustrated embodiments are only preferred examples of the invention andshould not be taken as limiting the scope of the invention. Rather, thescope of the invention is defined by the following claims. We thereforeclaim as our invention all that comes within the scope and spirit ofthese claims.

We claim:
 1. A prosthetic heart valve, comprising: an annular framecomprising an inflow end and an outflow end and being radiallycompressible and expandable between a radially compressed configurationand a radially expanded configuration; a leaflet structure positionedwithin the frame and secured thereto; and an outer sealing membermounted outside of the frame and adapted to seal against surroundingtissue when the prosthetic heart valve is implanted within a nativeheart valve annulus of a patient, the sealing member comprising a meshlayer and pile layer comprising a plurality of pile yarns extendingoutwardly from the mesh layer.
 2. The prosthetic heart valve of claim 1,wherein the mesh layer comprises a knit or woven fabric.
 3. Theprosthetic heart valve of claim 1, wherein the pile yarns are arrangedto form a looped pile.
 4. The prosthetic heart valve of claim 1, whereinthe pile yarns are cut to form a cut pile.
 5. The prosthetic heart valveof claim 1, wherein the height of the pile yarns varies along a heightand/or a circumference of the outer skirt.
 6. The prosthetic heart valveof claim 5, wherein the pile yarns comprise a first group of yarns alongan upstream portion of the outer skirt and a second group of yarns alonga downstream portion of the outer skirt, wherein the yarns of the firstgroup have a height that is less than a height of the yarns of thesecond group.
 7. The prosthetic heart valve of claim 5, wherein the pileyarns comprise a first group of yarns along an upstream portion of theouter skirt and a second group of yarns along a downstream portion ofthe outer skirt, wherein the yarns of the first group have a height thatis greater than a height of the yarns of the second group.
 8. Theprosthetic heart valve of claim 5, wherein the pile yarns comprise afirst group of yarns along an upstream portion of the outer skirt, asecond group of yarns along a downstream portion of the outer skirt, anda third group of yarns between the first and second group of yarns,wherein the yarns of the first and second groups have a height that isgreater than a height of the yarns of the third group.
 9. The prostheticheart valve of claim 1, further comprising an inner skirt mounted on aninner surface of the frame, the inner skirt having an inflow end portionthat is secured to an inflow end portion of the outer sealing member.10. The prosthetic heart valve of claim 9, wherein the inflow endportion of the inner skirt is wrapped around an inflow end of the frameand overlaps the inflow end portion of the outer sealing member on theoutside of the frame.
 11. The prosthetic heart valve of claim 1, whereinthe mesh layer comprises a first mesh layer and the outer sealing memberfurther comprises a second mesh layer disposed radially outside of thepile layer.
 12. The prosthetic heart valve of claim 1, wherein the outersealing member is configured to stretch axially when the frame isradially compressed to the radially compressed state.
 13. The prostheticheart valve of claim 1, wherein the mesh layer comprises warp yarns andweft yarns woven with the warp yarns, and the pile layer comprises thewarp yarns or the weft yarns of the mesh layer that are woven or knittedto form the pile yarns.
 14. The prosthetic heart valve of claim 1,wherein the mesh layer comprises a woven fabric layer and the pile layercomprises a separate pile layer that is stitched to the woven fabriclayer.
 15. The prosthetic heart valve of claim 1, wherein the mesh layerhas a first height extending axially along the frame and the pile layercomprises a second height extending axially along the frame, wherein thefirst height is greater than the second height.
 16. The prosthetic heartvalve of claim 15, wherein the mesh layer extends closer to the outflowend of the frame than the pile layer.
 17. A prosthetic heart valve,comprising: an annular frame comprising an inflow end and an outflow endand being radially compressible and expandable between a radiallycompressed configuration and a radially expanded configuration; aleaflet structure positioned within the frame and secured thereto; andan outer sealing member mounted outside of the frame and adapted to sealagainst surrounding tissue when the prosthetic heart valve is implantedwithin a native heart valve annulus of a patient, the sealing membercomprising a fabric having a variable thickness.
 18. The prostheticheart valve of claim 17, wherein the thickness of the fabric layervaries along a height and/or a circumference of the outer sealingmember.
 19. The prosthetic heart valve of claim 17, wherein the fabriccomprises a plush fabric.
 20. The prosthetic heart valve of claim 17,wherein the fabric comprises a plurality of pile yarns and the height ofthe pile yarns varies along a height and/or a circumference of the outerskirt.
 21. The prosthetic heart valve of claim 20, wherein the pileyarns comprise a first group of yarns along an upstream portion of theouter skirt and a second group of yarns along a downstream portion ofthe outer skirt, wherein the yarns of the first group have a height thatis less than a height of the yarns of the second group.
 22. Theprosthetic heart valve of claim 20, wherein the pile yarns comprise afirst group of yarns along an upstream portion of the outer skirt and asecond group of yarns along a downstream portion of the outer skirt,wherein the yarns of the first group have a height that is greater thana height of the yarns of the second group.
 23. The prosthetic heartvalve of claim 20, wherein the pile yarns comprise a first group ofyarns along an upstream portion of the outer skirt, a second group ofyarns along a downstream portion of the outer skirt, and a third groupof yarns between the first and second group of yarns, wherein the yarnsof the first and second groups have a height that is greater than aheight of the yarns of the third group.